Oil burner and fuel feed system



July 15, 1952v F. R. HUSBAND 2,603,278

OIL BURNR AND FUEL. FEED SYSTEM FOR`SAME Filed Feb. 4, 1948 Patented July 15, 1952 reise o'IL BURNER AND FUEL FEED SYSTEM Fon sAME Frederick Ritchie Husband', Thames, Auckland, New Zealand Application February 4, 1948,'Serial No.` 6,127

In New Zealand December 19, 1946 The invention relates" to Voil burners'and fuel feed systems for same, wherein liquid fuel is pre-heated and vaporized for'passing to. a combustien space for the purpose of generating heat.v

In known oil burning systems of the kind aforesaid, internal pressure `generated at the burner, actsto retard the flow of fuel to the latter,l necessitating the employment of means to` create a; counterpressure, and apply Vthe lat"- terV behind the fuel, as for instance', by the introduction of pressure into the fuel tankv inorder to force the fuelto the burner, so that the latter may function.

The use of special' pressure creating means,

and-the application of same to fuel supply ysys-- tems of oil burners for the purpose indicated, present disadvantages not readily overcome, and which up to the present have restricted development of the aforesaid .class of burner by limi-ting. its application to smaller types of appliances,because as the burners increase in size, the creation of and the application of the counterpressure behind the fuel, becomes a problem of considerable magnitude, until a point is reached when'pthis class of. burner can not be economically used. y

, The primary object of the invention is, therefore, to provide for use .with oil burners of the kindV referred to,. a fuel feed system which avoids or' overcomes the disadvantage of the use vof specialy pressure creating and applyingy means, by utilizing .pressure created at the burner, in such a manner that as far as the supply of fuel tothe latter is concerned, said pressure cancels itself out, .and the fuel is enabled to pass to the burner by'gravity. 0rv in other Words, there ,is provided a fuel feed system wherein the fuel,

although subjected to' pressure, passes to the burner by gravity.

The placing of the fuel under pressure, While it remains gravity operated,` enables the pressure generated in the system to `be taken advantage of v:for the purpose of controlling the fuel supply to the burner, and consequently also the heat generated4 thereby, introducing a safety measure in the operation of the burner.

lli-special'V advantage arising out of the dispensing With of the pressurecreating and applying means, is the simplification of the construc-` tion and the operation of the system, which enables the field of application of the burner tobe extended, regardless ofthe type and size of appliance iny connection with whichthe burner andthe improvedfuel Afeed system are used.

9 Claims. (Cl. 158-63) Y Other objects of the invention, are to increase the efliciency of the burner by ensuring more complete and effective combustion of the fuel, Which gives increased heat with economyl in fuel consumption, and cleanliness owing tothe elimination of smoke, soot and other residue, and also to provide a simple and fool proof supply system, the operation of which can be controlled by the regulation rof the flow of fuel, either manually or automatically, or both, to give increased or decreased heat as required, said jsystem also including a further safety feature provided by a vacuum seal whichl operates automatically onv the fuel supply line, to close saine if'necessary, and automatic metering of fuel to the burner for priming same.

Briefly, the essential feature of the invention, may be. said to consist in providing, through an oil fuel burner of the kind aforesaid, ,and a source of fuel supply, a circuit whereby pressure generated under heat at the burner, is directedrto behind or above the fuel, to provide in said circuit a Ybody of fuel, which is subjected, at' opposite sides, to cppcsitely acting equal pressures, whereby 'there is lcreated a condition which enables the fuel While'u-nder pressure, to pass to the burner by gravity'. f

vAnother feature comprised in the invention, is the provision in' the burner of an expansion chamber wherein the vaporized fuel is superheated/and expanded before being delivered to the combustion" area, with the result that reduced airis required to SuppQ'rt combustion, and combustion efficiency is increased.

VA further featureV is the provision of meansl in the expansion chamber for creating a vac'-I uum seal in the fuel supply tank, and thereby preventing :the flow of fuel to the burner in the event of the latter ceasing to function, or should the fuel supply lcontrol cock be inadvertently opened, said means also to the expansion chamber, burner..

OtherY features include a limiting jet in the when starting up' the fuel supply line as a vsafeguard against excesfeatureswhich"Willb'ecome apparent froma *studyV of the" following description and accompanying serving' to meter fuell illustrations, combine to produce the improved oil burner and fuel feed system for same, but it must be clearly understood that the description to be herein given, and the illustrations, are by way of example only, and that the invention is not restricted to the form described and shown, as it will be apparent that the actual apparatus which may be used, will vary considerably in accordance with the type of appliance to which the burner is applied, and the conditions under which the latter operates, the essential features which combine to provide the invention remaining the same in all cases.

For a further understanding of the invention, reference is made to the accompanying drawings, wherein:

Figure 1 illustrates in diagrammatic form, the layout or principle upon which the burner and the fuel feed system for same, operate, while Figure 2 shows partly in sectional elevation, and partly in elevation, one practical form the invention can take, and,

Figure 3 is a vertical sectional view through the pressure regulator.

Referring to Figure l of the drawings. I indicates a liquid fuel supply tank, 2 the expansion chamber of a burner, and 3 the jet at which gas burns to heat the chamber 2, gas being supplied to the jet 3 by the tube 6 from the chamber 2; 4a indicates an oil fuel line between the tank I and a pressure regulator i6 and 4 indicates a continuation fuel line to a vaporizer tube which opens into the expansion chamber 2, said fuel line 4 having incorporated therein a fuel control cock "I, while 8 is a pressure take off tube leading from the expansion chamber 2 and placed in communication with the top of the fuel tank I, by a pressure line 9.

With the burner functioning, after having been primed and preheated, and with the control cock 'I open, fuel passes from the tank I via the line 4a,4 to the vaporizer tube 5 from which it enters the chamber 2, and is converted into gas and expanded therein to generate pressure, some of the gas under pressure passing to the jet 3, and some passingvia the line 9 to the top of the tank I, to behind or above the fuel therein.

The effect of transferring pressure from the chamber 2 to the tank I through the line 9, is to apply behind or above the fuel, that is in the top of the tank I, a pressure equal to the back pressure which acts in the tube 5 against the now of fuel in the line 4 to said tube, the result of which is that the fuel is located between two equal pressures which act on the fuel in opposite directions, and so counterbalance or cancel each other out, thereby leaving the fuel free to flow by gravity through the line 4a-4 to the tube 5, to be vaporized therein and passed to the chamber 2 for conversion into gas which is superheated and expanded in said chamber.

By applying equal cppositely acting pressures at opposite sides of the fuel, the latter is put into a stateof compression, and advantage can be taken of this condition to provide a convenient method of flame or heat control as will be hereinafter described.

The cycle described will continue to operate as long as fuel is permitted to flow through the line 4 to the vaporizer tube 5.

The foregoing is intended merely to explain the principle or essential feature of the invention, which will now be described in greater detail as embodied in one practical form, suitable 4 for use in the furnace or firebox of an appliance. such as, for instance, a hot water heater.

As illustrated in Figure 2, there is provided a front plate II containing air ports II, and adapted to serve as a coverplate to a furnace or rebox, and from which plate I I there extends a housing I2 adapted for insertion in the furnace or firebox.

The fuel tank I is supported by a supporting member 30 a suitable height above the housing I2 to give a desired head of fuel, and so as to be located outside the furnace or frebox when the housing I2 is inserted therein.

The burner comprising the expansion chamber 2 provided with the tubes 5, 6 and 8, and gas nipple jet 3 aforesaid, is located in the housing I2 the required distance from the plate II, and has surrounding its lower portion an inverted combustion cone I3 positioned to provide between itself and the lower portion of the chamber 2 a combustion area I4.

The combustion cone I3 is open at the top, and also at the bottom, and below it is located a cup or depression I5 in the bottom of the housing I2, to hold liquid fuel used in pre-heating the chamber 2 at the commencement of operations.

The fuel tank I is provided with a filler cap I', and is a sealed unit when in use, and if desired, it can be provided with means which automatically act to close the tank outlet to the fuel line 4a upon the filler cap I being removed, as for instance, when it is necessary to place fuel in the tank I This is a safety precaution to prevent flooding of the burner during the filling operation, should the fuel control cock 'I have been left open, said cock comprising a plain needle valve fitted in the fuel line 4 as close as possible to the vaporizer tube 5.

The fuel line 4a leads downwards from the tank I, and then upwards and to the vaporizer tube 5, a pressure regulator I6 being inserted between the sections 4a and 4 of the fuel line so as to enable the state of compression imposed on the fuel by the cppositely acting pressures, to be utilized for the purpose of providing a rcnethod of flame or heat control before referred A heat exchanger IIJ provided in the line 9 and through which the fuel line 4 passes, enables heat in the gas passing from the chamber 2 to the tank I, to transfer to fuel passing from the latter to the vaporizer tube 5, thereby preheating the fuel before itreaches the vaporizer tube 5, and reducing the temperature of the gas under pressure in the line 9 before said gas reaches the tank I.

As the heated fuel tends to rise, it is essential that the fuel line 4 from the regulator IB be installed so as to have a continuous slope upwards through the heat exchanger` I 0 to a point beyond same, in order to facilitate the' tendency of the fuel after being heated in the heat exchanger III. to rise, as if the line 4 was given a downward slope, a condition of turbulence would be created in the line, owing to the heated fuel trying to climb against the flow from the tank I.

Vaporization commences after the fuel has emerged from the limiting jet I8. The upward slope of the fuel line 4 is to avoid conditions of turbulence in the fuel line due to the effects of the hot fuel climbing back to the tank I, against the cold fuel coming down. The slope given to the fuel line 4 as it leaves the heat exchanger I9 avoids this condition. Giving the fuel line a downward slope before it enters the heat vencchanger I provides a cold fuel trap, which eiectively prevents the hot fuel from flowing back to the tank I.

The pressure regulator I6 is of conventional designand may comprise a Valve adapted to seat upon a valve seat 2| positioned in an axial bore through the body of the regulator, which bore forms a connection between the fuel line 4a from the tank I and the fuel line il to the burner.

The valve 29, which is spring loaded, is provided with a valve stem 22 having a thrust collar 23 thereon bearing against a ilexible diaphragm 24, housed within a diaphragm chamber 25; The diaphragm 24 is adapted to be controlledby a diaphragm loading spring 26 mounted within a sleeve 2l and positioned in the body of the regulator so that the action of` this loading spring upon the diaphragm 24 is opposed tothe action of the spring loaded valve stem 2'2 upon the opposite side of the latter. The modulus of the loadingspring 26 can be regulated by a knob Illa mounted on a thrust rod 28 and bearing against the loading spring.

.The loading spring 2S is adjusted to maintain the valve 23 oi the seat 2I to leave the channel through the regulator open, and the modulus of the loadingspring 25 is variable by means ofthe knobV Illa on the thrust rod 28, so that the loading can be regulated to withstand only a predetermined pressure arising out of the compression of the fuel between the oppositely acting pressures on the diaphragm 2li. Thus, when said predetermined pressure is exceeded the valve 29 closes on its seat 2| and cuts off the supply-of fuel from the line l through the line sa to the burner, thereby putting the latter out of action.

In order to prevent the generation of pressures in the system which could be dangerous, precautions are taken to prevent such a condition arising, a limiting jet I3 being inserted in the fuel line 4 at the entrance to the vaporizer tube 5, to restrict fuel delivered to the latter, to an amount sufficient to obtain a desired degree of heat, the orice of the limiting jet I8 being selected in relation to the orice of vthe gas nipple jet 3, sov

as to' provide a variety of flame and pressure con-v ditions, suitable for diiferent uses.

Both the limiting jet I 8 and the gas nipple jet 3 are of'conventional form.

The pressure line 9 leads from the pressure take oit tube 8, which extends into the expansion chamber 2, upwards to the top of the tank I, the lower portion of the line entering the heat exchanger `III at the bottom of one end thereof, while the upper portion of said line 9 leaves the opposite end of they heat exchanger I0 from the top. thereof.

` It is essential that the pressure line 9 be installed with a continuous upward slope to the tank I, and that the heat exchanger I be of such. construction, the accumulations 'of liquid in the line 9Y and heat exchanger I 0 are avoided, as such accumulations would be responsible for fthe formationV of pressure locks in the line 9, and prevent; the full now of gas to the tank I, which would result in fuel ceasing to now through the fuel line 4 to the burner.

VAs the gas under pressure passing through the line 9 from the expansion chamber 2 to the tank I,is heated to a high temperature, and as it is undesirable that. gas at high temperature should be delivered into thetank I, means are provided for effecting a reduction in the temperature of the. gas prior to its entering the tank I, and t0 eiec't suchv reduction in: temperature, a7 reducing jet I'I `is provided at the outlet end of the pressure take off tube 8. Furthermore, additional heat. is extracted from the gas in the heat exchanger I0, whichserves as an expansion chamber for the gas, from which heat is absorbed by conduction into the fuel in the line 4 by the gas coming into contact with thelatter Whereit passes through the heat exchanger I0. i

The cooling of the gas by limiting the flow thereof by means of the reducing ljet I'I. permits a greater degree of expansion of the gas in the pressureline the heat exchanger IG, andthe tank I. The reducingjet l1 has a small bore therethrough and this permits of a certain degree of expansion in line with resultant cooling, this iet. also operating to a limited extent as a vliow regulator. This latter action results from/the condensation factor, due to the radiation effects of the metal exposed to the air in the fuel-tank i and associated piping lia-l from the tank. By

limiting the gas `ilow through the reducing jet I1, due to the very small bore therein, the expansion` factor in line 9 is increased, but at the same time the radiation effect resulting incooling is also more effective. Therefore, as expansion of the gas with resultant cooling is obtained in line 9, due to the small bore of the reducing jet I'l, and now regulation is not required in the sense of actually regulating the now of the gas, it is the factor of expansion which determines the func'- tion of the jet il as a reducing jet.

The absorption of heat from the gas in the heat exchanger l, by fuel in the line 4, not only lowers the temperature of the gas, but also raises vthe temperature of the fuel, which lowers the rviscosity of the latter, rendering it more readily susceptible to vaporization in the tube 5, thereby obtaining the dual eiect of maintaining a more yuniform rate of gain, together with acceleration in the speed with which working pressuresfare obtained. 4 The vaporizer tube 5, and the pressure take off' tube 8, are' carried downwards in the expansion chamber 2, so that their open inner and lower ends terminate in similar pressure areas, or nearly so, and when starting up the burnenthe tube '5 delivers liquid fuel into the expansion chamber 2, which under these circumstances, acts as the vaporizer for starting up purposes.

When, however, suiicient heat is being-generated, vaporization of the fuel is effected in the tube 5, and the chamber 2 resumes its proper function of permitting the gasto expandv under the action of the heat from the flame in. the combustion area I Il, and by these means con'- siderable expansion of the gas is obtained .before it is projected into the combustion area I4,and as a result, less air is required to supportcombustion, and increased combustion eiiiciency is, obtained. l Besides providing means for taking of pres-v sure from the expansion chamber 2, for transfer 'to the tank I to. be applied behind 'the fuel therein, the tube 5 enables automatic control of thev supply of fuel toI the burner to be obtainedas follows,

When the fuel control cock 'I is opened to prime the burner, in starting up the latter, air

:passes into the tank I to replace the outgoingv fuel, by way of the gas nipple jet 3, tube Fi, chamber 2, tube 8 and line 9, so that by carrying the tube 8 well down in the expansion chamber 2, and terminating it at a predetermined distance Afrom the bottom thereof, two important effects f can. be, obtained.:

(1) Automatic regulation o-f the amount of fuel delivered into the chamber 2 for priming purposes, by positioning the lower open end of the tube 8 below the level of fuel required for priming, so that when the fuel reaches said level. it closes the air passage to the tank I, and sets up a vacuum seal therein, which prevents fuel from flowing from the tank I until the seal is broken.

(2) The automatic safety vacuum seal also operates as in (l), in cases where the fuel control cock 'I has been accidentally or otherwise opened, without the burner being started up.

The vacuum seal referred to in (l) and (2), is broken upon the fuel in the chamber 2 being fvaporized and converted into gas, when the chamber 2 is heated, the establishing of the seal and the breaking of same being automatic.

The lower end of the gas tube 6 carries the gas nipple jet 3, which is directed towards the expansion chamber 2, the tube 6 being bent to the required angle, and taken through the bottom of the chamber 2, and continued upwards inside same, so that its upper end is as close to the top thereof as possible, thereby establishing a considerable distance between the open end of tube 6, and the open end of pressure take off tube Il, to provide a satisfactory safety margin in which to establish the Vacuum seal before referred to.

Air to support combustion at the burner is admitted via the holes I Ia in the cover plate I Land the housing I2, to the combustion area I4, and provisioncan be made by means of a shutter acting in relation to the holes II n the coverplate I I, if desired.

It is desirable that a filter |19 be inserted in the fuel line 4a, between the tank I and the regulator I6.

In order to operate the burner, a small quantity of methylated spirit or other volatile fuel is placed in the cup or depression I5, in the housing I2, by any convenient means, and ignited, a door being provided in the side of the housing I2, in the apparatus illustrated in Figure 2, to enable this to be done, following which the fuel control cock 'I is opened to the full extent, which operation also opens the air admission holes Ile.

The regulator I6 is set to the setting which will permit only the maximum heat required, to be generated.

Fuel now flows via the line 4 and vaporizer tube into the expansion chamber 2, until it reaches the level covering the lower end of the pressure take off tube 8, whereupon the vacuum seal is set up in the tank I, and fuel ceasesgto flow from same.

Under the action of heat from the burning of the preheating fuel in the cup or depression I5, the fuel in the chamber 2 is vaporized and converted into gas under pressure, some of which passes to the gas nipple jet 3, via the tube 6, and is ignited and assists in further heating the chamber 2.

At the same time gas under pressure passes via the line 9 to the tank I, and breaks the vacuum seal imposed on the fuel, in the process of priming the burner. Y

As soon as the vacuum seal is broken, more fuel will be supplied to the vaporizer tube 5 and expansion chamber 2, and consequently more gas will be generated, and the pressure will begin to rise, and as it is impossible for the pressure to rise until gas is being generated freely, no risk of flaring from the discharge of raw fuel is involved when operating the burner.

The combination of jets is such that more fuel will be delivered than is required to produce the gas to feed the flame, at the burner. therefore there is a constant increase in pressure throughout the system, until the point is reached where the gas being consumed, equals the fuel being delivered.

Control of the fuel is exercised in two ways:

(l) Automatically, by means of the pressure regulator I6, according to its setting, and. (2) Manually, by means of the control cock 1 thereby providing for complete and positive control of the burner at all times.

Although the burner operates satisfactorily, on low heads of fuel, it is susceptible to changes of fuel level, when operating on low heads. which necessitates periodic adjustment of the fuel control cock 1, to keep the operating pressure steady, the use of the pressure regulator I6, and suitable elevation of the tank I, however. giving a continued steadier performance and avoiding the necessity for such adjustment. This particularly applies if the tank I is mounted with its longitudinal axis horizontal, as opposed to vertical.

What I do claim and desire to obtain by Letters Patent of the United States of America is:

l. An oil burner and fuel feeding system for same comprising a fuel tank, a circuit comprised in part by a fuel line extending from the tank. a heat interchange device through which the fuel line passes and an expansion chamber into which the fuel line leads, and said circuit including also a back pressure line extending from the expansion chamber through the heat interchange device to the fuel tank above the fuel level therein.

2. An oil burner and fuel feeding system as recited in claim 1 in which the fuel line intermediate the fuel tank and the burner includes pressure regulating means operated by the differential between the gravity flow in the fuel line and the back pressure in the back pressure line.

3. An oil burner and fuel feeding system as recited in claim 1 in which the circuit includes a vaporizer tube projecting into the expansion chamber and to which the fuel line is connected and a pressure take off tube extending from the expansion chamber to which the back pressure line is connected.

4. An oil burner and fuel feeding system as recited in claim 1 in which the expansion chamv ber is provided with a gas nipple jet connected thereto by a tube which tube conducts gas to the gas nipple jet from the expansion chamber and the gas nipple jet and tube conducts air to the expansion chamber and the back pressure line when the burner is not operating.

5. An oil burner and fuel feeding system as recited in claim l in which the back pressure line is connected to the expansion chamber by a pressure take off tube extending adjacent the bot-- tom of the expansion chamber whereby its inner end will be closed by liquid fuel collecting in the expansion chamber for the purpose of enabling a vacuum seal to be established in the fuel tank.

6. An oil burner and fuel feeding system as recited in claim 1 in which the fuel line intermediate the fuel tank and the burner includes pressure regulating means operated by the differential between the gravity flow in the fuel line and the back pressure in the back pressure line, a vaporizer tube extending into the expansion chamber and a limiting jet intermediate the pressure regulating means and the vaporizer tube.

7. An oil burner and fuel feeding system as recited in claim 1 in Which the fuel line intermediate the fuel tank and the burner includes pressure regulating means operated by the differential between the gravity iiow in the fuel line and the back pressure in the back pressure line, a vaporizer tube extending into the expansion chamber, a manually operated valve intermediate the pressure regulating means and the vaporizer tube, and a limiting jet intermediate the manually operated valve and the vaporizer tube.

8. An oil burner and fuel feeding system is recited in claim 1 in Which the back pressure line is connected to the expansion chamber by a pressure take olf tube and a reducing jet is incorporated in the back pressure line adjacent the pressure take off tube for effecting a reduction in temperature of the gas Which passes through the back pressure line.

9. An oil burner and fuel feed system for the same comprising, a cover plate having air admission holes therein cooperable with a furnace or fire box or the like, a housing extending from the cover plate and adapted for insertion in the furnace or fire box, a fuel tank supported by' said plate, said housing having an expansion chamber therein, an inverted combustion cone mounted in spaced relation to the expansion chamber to provide a combustion area between the expansion chamber and the cone, a fuel line 10 extending from the fuel tank to the expansion chamber and including a pressure regulator, a control cock, a limiting jet, and a vaporizing tube extending into the expansion chamber, a pressure take off tube leading from the expansion chamber and having a reducing jet therein, a pressure line leading from the pressure take off tube to the fuel tank, a heat exchanger through which the fuel and pressure lines pass, a gas tube leading from the expansionvchamber and a gas nipple jet on said gas tube for burning gas to heat said expansion chamber.

FREDERICK RITCI-IIE HUSBAND.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 235,673 Donovan Dec. 21, 1880 715,354 Dawson Dec. 9, 1902 1,254,768 Bothwell Jan. 29, 1918 y2,113,252 French Apr. 5, 1938 2,200,826 Johnson May 14, 1940 2,450,025 Stein Sept. 28, 1948 FOREIGN PATENTS Number Country Date 336,654 Great Britain Oct. 17, 1930 

